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querying-pinot.md

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Learn how to query Pinot using SQL

Querying Pinot

SQL Interface

Pinot provides SQL interface for querying. It uses the Calcite SQL parser to parse queries and uses MYSQL_ANSI dialect. You can see the grammar in the Calcite documentation.

Limitations

  • The latest Pinot multi-stage supports inner join, left-outer, semi-join, and nested queries out of the box. It is optimized for in-memory process and latency.
    • For queries that require a large amount of data shuffling, or require spill-to-disk, or hitting any other limitations of the multi-stage engine, we still recommend using Presto. For more information, see Multi-Stage Query Engine Page.
  • The latest Pinot also supports simple DDL to insert data into a table from file directly. For more info please see the 0.11.0 release note.
    • More DDL supports will be added in the future. But for now, the most common way for data definition is via the REST API.

Identifier vs Literal

In Pinot SQL:

  • Double quotes(") are used to force string identifiers, e.g. column names
  • Single quotes(') are used to enclose string literals. If the string literal also contains a single quote, escape this with a single quote e.g '''Pinot''' to match the string literal 'Pinot'

Mis-using those might cause unexpected query results:

e.g.

  • WHERE a='b' means the predicate on the column a equals to a string literal value 'b'
  • WHERE a="b" means the predicate on the column a equals to the value of the column b

If your column names use reserved keywords (e.g. timestamp or date) or special charactesr, you will need to use double quotes when referring to them in queries.

Note: Defining decimal literals within quotes preserves precision.

Example Queries

Selection

//default to limit 10
SELECT * 
FROM myTable 

SELECT * 
FROM myTable 
LIMIT 100

SELECT "date", "timestamp"
FROM myTable

Aggregation

SELECT COUNT(*), MAX(foo), SUM(bar) 
FROM myTable

Grouping on Aggregation

SELECT MIN(foo), MAX(foo), SUM(foo), AVG(foo), bar, baz 
FROM myTable
GROUP BY bar, baz 
LIMIT 50

Ordering on Aggregation

SELECT MIN(foo), MAX(foo), SUM(foo), AVG(foo), bar, baz 
FROM myTable
GROUP BY bar, baz 
ORDER BY bar, MAX(foo) DESC 
LIMIT 50

Filtering

SELECT COUNT(*) 
FROM myTable
  WHERE foo = 'foo'
  AND bar BETWEEN 1 AND 20
  OR (baz < 42 AND quux IN ('hello', 'goodbye') AND quuux NOT IN (42, 69))

For performant filtering of ids in a list, see Filtering with IdSet.

Filtering with NULL predicate

SELECT COUNT(*) 
FROM myTable
  WHERE foo IS NOT NULL
  AND foo = 'foo'
  AND bar BETWEEN 1 AND 20
  OR (baz < 42 AND quux IN ('hello', 'goodbye') AND quuux NOT IN (42, 69))

Selection (Projection)

SELECT * 
FROM myTable
  WHERE quux < 5
  LIMIT 50

Ordering on Selection

SELECT foo, bar 
FROM myTable
  WHERE baz > 20
  ORDER BY bar DESC
  LIMIT 100

Pagination on Selection

Results might not be consistent if the order by column has the same value in multiple rows.

SELECT foo, bar 
FROM myTable
  WHERE baz > 20
  ORDER BY bar DESC
  LIMIT 50, 100

Wild-card match (in WHERE clause only)

To count rows where the column airlineName starts with U

SELECT COUNT(*) 
FROM myTable
  WHERE REGEXP_LIKE(airlineName, '^U.*')
  GROUP BY airlineName LIMIT 10

Case-When Statement

Pinot supports the CASE-WHEN-ELSE statement.

Example 1:

SELECT
    CASE
      WHEN price > 30 THEN 3
      WHEN price > 20 THEN 2
      WHEN price > 10 THEN 1
      ELSE 0
    END AS price_category
FROM myTable

Example 2:

SELECT
  SUM(
    CASE
      WHEN price > 30 THEN 30
      WHEN price > 20 THEN 20
      WHEN price > 10 THEN 10
      ELSE 0
    END) AS total_cost
FROM myTable

UDF

Functions have to be implemented within Pinot. Injecting functions is not yet supported. The example below demonstrate the use of UDFs.

SELECT COUNT(*)
FROM myTable
GROUP BY DATETIMECONVERT(timeColumnName, '1:MILLISECONDS:EPOCH', '1:HOURS:EPOCH', '1:HOURS')

For more examples, see Transform Function in Aggregation Grouping.

BYTES column

Pinot supports queries on BYTES column using HEX string. The query response also uses HEX string to represent bytes values.

e.g. the query below fetches all the rows for a given UID.

SELECT * 
FROM myTable
WHERE UID = 'c8b3bce0b378fc5ce8067fc271a34892'